Peripheral β-Adrenoceptor Responsiveness in Young Normotensive and Hypertensive Subjects

In young subjects with normal blood pressure (N = 10) or with mild (n = 6) or moderate (n = 8) hypertension we assessed the effects of increasing doses of i.v. isoproterenol (each dose for 10 min) on systolic and diastolic blood pressure, heart rate, plasma renin activity (PRA), serum potassium and free fatty acids (FFA). Except for blood pressure, basal levels did not differ significantly between the groups. Isoproterenol induced dose-related increases in systolic blood pressure, heart rate and PRA, and dose-related decreases in diastolic blood pressure. Neither the threshold dose (i.e. the lowest dose significantly affecting these parameters), nor the changes induced by the higher doses differed between the normotensive and hypertensive subjects. Levels of serum potassium and FFA, obtained at the end of the infusion, also did not differ significantly between the groups. These results indicate, that in contrast to older and/or more severely hypertensive subjects, young subjects with mild to moderate hypertension have a peripheral beta-adrenoceptor responsiveness similar to that of normotensive controls.